Reclaimer for pulp-mills.



Patented Mar.r|2, |901.

N.v C. HODGKINS. i Y

RECLAIMER ForrPuL-P MILLS.

` (Application iled Apr. 23, 1900.) m0 Model.) 3 sheets-sheet 1.

m: Noms versus Fucrmhmd.. wAsmnovomqx;

Patented Mar. I2. |90I.

N. c. H-onakms. m-:cLAImEn Fon PULP mLLs.

(Application filed Apr. 23, 1900.) (No Model.)

3 Shegis-Sheet 2.

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No. 669,748. Patented MarI I2, |901. N.v C. HODGKINS.

BECLAIMER FUR PULP MILLS.

(Application led Apr. 23, 199D.) (No Model.) 3 Sheets-Sheet 3.

,THE nofws Psrzns oo., momumo.; wAsHmsYoN. u. c.

NELSON O. HODGKINS, OF AUGUSTA, MAINE, ASSIGNOR OF ONE-HALF TO LEWIS H. SANFORD, OF SAME PLACE.

RECLAHVIER FOR PU LP-lVIILLS.

SPECIFICATION forming partof Letters Patent N o. 669,748, dated March 12, 1901.

Application led April 23, 1900.

To all whom t may concern,.-

Be it known that I, NELSON C. HoDeKINs,

a citizen of the United States, residing at Augusta, in the county of Kennebec and State of Maine, have invented a new and useful Reclaimer for Pulp-Mills, of which the following is a specification.

My invention is an improved reclaimer for pulp-mills, one object ofV my invention being to provide an apparatus which is adapted to reclaim the liquor which is vented fromthe digester and convey the same to a suitable receiver, either a storage-tank or one of the tanks in the acid system.

A further object of m y invention is to provide an apparatus Which is adapted to reclaim the sulfurousacid gas from the impure red liquor and add said reclaimed sulfurous-acid gas either to the sulfurous acid in the storagetank or in the acid system.

In apparatus for digesting wood for the making of paper-pulp therefrom the liquid which is first vented from the digester is practically as strong and pure as it was originally, and such liquid is by my apparatus prevented from going to waste and conserved for future use; but in the subsequent venting of the digester the liquor is impure, of a reddish color, owing to the presence of the impurities therein, and such red liquor, as it is termed in the art, has been heretofore wasted, although it contains a percentage of gas which is valuable as an element of strength in the digestive liquor.

One object of my invention is to provide an apparatus which is designed to cool the pure digestive liquor which is vented from the digester, condense the same, reclaim it, and convey such reclaimed liquor to a suitable receiver.

Another object of my invention is to provide an apparatus which is adapted for the purpose of separating the valuable gas from the otherwise Worthless red liquor, reclaim such gas, and add the same to the pure liquor in a receiver, thereby adding to the strength of such liquor.

My invention consists in the novel. construction and combination of devices' hereinafter fully set forth, and pointed out in the claims.

In the accompanying drawings, Figure 1 is Serial No. 13,960. (No model.)

,a verticalsectional view of a gas-separator for reclaiming the gas from the vented liquor embodying my improvements, the same be ing shown in operative relation to a digester. Fig. 2 is a diagrammatic elevation of a pulpdigesting apparatus provided with reclaiming apparatus embodying my improvements. Fig. 3 is a similar v iew of a modiled form of the same.

The digesters A are each provided at the top with a vent-pipe 10, and each vent-pipe 10 is connected with a separator 11. A pipe 12 is carried from each separator to a receptacle 13, closed at the top and at the bottom, and said pipes 12 from the separatorsextend nearly to the bottoms of the receptacles. Each receptacle is supplied at the bottom with cold water through the medium of a pipe 14, and each receptacle 13 is further provided atits upper portion with an outlet-pipe 15, which may lead to a sewer or other suitable point and through which the waste Waterand liquor are discharged. The cold water flowing up through the receptacle 13 around the pipe 12 therein cools the liquor and at the same time a trap is formed acting to arrest the gas.

In the digestion of wood and reduction of the same to pulp in my improved apparatus the digesters A are filled with Wood chips charged with sulfurous acid and heated by steam, the cooking process continuing about seven hours. It is necessary to entirely lill the digesters With the chips and the cooking liquor or acid, so that the chips'will be entirely submerged and those at the top of the digesters prevented-from burning during the initial stages of the cooking. After a time the chips become entirely saturated and tend to sink, and when the temperature has been raised to about 120o Fahrenheit the first venting occurs, the liquor vented being practically pure sulfurous acid. This venting is effected by opening a valve 10, thereby permitting the vented liquor to pass into the separator 11, from which, the valve 16 being closed, the liquor passes through the pipe 17 to the drum 18 and from the latter through the pipe 2O to a receiver, which may be either .a storage-tank C, as shown in Fig. 2, or a tank 25 in the acid system, as shown in Fig. 3. When the liquor shows a reddish color, indi- IOO eating that it has lost its strength and contains only a small percentage of gas, the liquor is worthless, but the gas is valuable, and it is desirable that even such small percentage of gas should be saved. To this end the red liquor is Vented into the separator 11, in which the pressure is reduced, the temperature correspondingly lowered, and a partial separation of the gas from the red liquor is effected, and the valve 16 being open the red liquor is permitted to pass downward from the separator through the pipe 12 and through the cold water in the trap 13. There being little pressure on the separator, gas released from the red liquor as it passes through the pipe 12 by the further reduction of temperature effected by the cold water in the trap will rise in said pipe 12 and following the line of least resistance returns to the separator through the pipe 12 and passes from the separator through pipe 17 to a receiver, as hereinafter more fully stated, while the refuse red liquor from which the has been separated flows to the sewer or is otherwise disposed of. The valve 16 is then closed.

The pipes 12 are straight and only one is employed in connection with each digester. Said pipes may be readily and expeditiously removed and others substituted when it is needful to cleanse them. This construction is advantageous and of importance in that the pipes 12 are thereby prevented from becoming clogged, thus obviating an objection to apparatus of this class heretofore employed, which are liable to become clogged frequently, rendering it necessary to shut down an entire line of digesters in consequence or to Vent directly into the air or sewer, and thereby lose all of the vented liquor'.

Itwill be understood that in my improved apparatus the gas is reclaimed from the liquor .of each digester separately, and hence that should an accident happen 'to any digester the others willtnot be affected. Furthermore, by providing an independent separator 11 for each digester A far better results are obtained than heretofore, the acid obtained having depreciated in strength to but a slight degree. Each separator 11 is connected with a drum 18 through the medium of a pipe 17, and each pipe 17 is provided with a valve 19, so that any individual separator may be cut off from the drum 18. A pipe 20, preferably of lead, is connected with the drum, and this pipe 2O is coiled in a cooling-chamber B, and the lower end 21 of the coil of said pipe 2O passes from said coolingchamber to a receiver. The said receiver m-ay be either a storage-tank (designated at C) or a tank of' the acid system. Cold Water is supplied through a pipe 22 to the bottom of the cooling-chamber. Said pipe 22 has a suitable valve 23, and a pipe 24: for waste Water is connected with the top portion of the cooler. Cold Water flows continuously into the cooling-chamber B and out of said chamber around the coils in the pipe 20, cooling the gas and liquor to the required temperature. By cooling to the required temperature before introducing the liquor and gas to the receiver. l dispense with a number of reclaiming tanks and also save the power eX- pended in pumping acid from one tank to another to effect the cooling under the ordinary process.

Before permitting the venting of the liquid from the digester the valve 16 is closed in the pipe 12 and the valve 19 opened in the pipe connecting the separator with the drum. The liquid which is iirst vented and which is practically as pure and strong as it was originally passes from the digester through the pipe 10 into the separator and from thence through the pipe 17 into the drum, from which it passes through the coil 2O in the cooling-chamber B. The temperature of the reclaimed liquid is reduced as it passes through the coil 2O to about 65o or 70o Fahrenheit before it is discharged into the receiver. This operation continues until the liquid assumes a reddish tinge, which may be ascertained by inspection of the glass gage on the separator,

when the valve 16 is then opened and the red liquor permitted to be discharged from the separator through the pipe 12 into the trap or receptacle 13, where it commingles with the water which circulates with the water in said trap through the water-pipes 14 15 and is discharged. yThe pressure in the separator being reducedand the temperature of the red liquor passing through the pipe 12 to the trap being lowered, the gas from the red liquor as it flows downward through said pipe 12 rises in the said pipe 12 into the separator, following the line of least resistance, and passes therefrom through the pipe 17, drum, and coil 2O into the receiver.

In my application for Letters Patent of the United States for a reclaimer for pulp-mills led May 16, 1899, Serial No. 717,001, I have described and shown the pipe 20, leading from the drum, as passing through the coolingchamberB and terminating in a storagetank. Under certain conditions, however, obtain better results by connecting the pipe 2O with a tank in the acid system which forms a suitable receiver for the reclaimed liquor and gas, the same being thereby united with the new 'liquor where the same is forming.

In the accompanying drawings, 25, 26, and 27 are respectively the first, second, and third tanks in the acid system employed in the manufacture of sulfurous acid with which to charge the digesters, said tanks being connected together by the pipes 28 or in any other suitable manner. A tank 29 for lime-water is connected with the first tank 25 by a valved pipe 30,and the third tank 27 is connected with the retort D, in which the sulfur is vaporized, by a pipe 31, Awhich includes a coil 32 in a cooling-chamber 33. A pipe 34 connects the tank 27 with the storage-tank C, a suitable pump (indicated diagrammatically at 35) being provided to convey the liquor or acid from IOO IIO

said tank 27 to the storage-tank C. B represents the usual vacuum-pump employed to draw the sulfur fumes from the retort through the lime-water in the tanks of the acid system, and said tanks are provided with the usual valved pipes 36, by means of which the lime- Water may be drawn from one tank into another. As herein shown, I connect the pipe 20 with the first tank 25 in the acid system, thereby causing the reclaimed acid or liquor to be added to the acid or liquor which is in process of formation. It will be understood that said pipe 20 may be connected with either of the tanks in the acid system.

In the method heretofore practiced of utilizing waste gases discharged from a digester in the -process of making sulfite pulp the same have been forced in a hot state into a new charge of cooking liquor at or near the bottom thereof. This process is not economical nor entirely efficient and differs from my process of reclaiming vented digestive acid and gas, in which I cool the vented acid and convey said reclaimed and cooled acid to a suitable receiver, either a tank in the acid system or a suitable storage-tank, before the same is reconveyed to the digester and used in another cooking charge. By my said improved method I am enabled to obtain much better results than have been heretofore possible and to save at least twenty per cent. more of the vented digestive liquor or acid. My said process forms the basis for another application for Letters Patent of the United States which I am about to make.

Having thus described my invention, I claiml. In a reclaimer for pulp-mills, the colnbination of a digester, a separator connected therewith and having means for the discharge of gas, a cooling-trap, and a connection between said trap and said separator, said trap forming a seal to prevent the escape of gas through the trap, substantially as described.

2. In a reclaimer for pulp-mills, the combination of a digester, a separator connected therewith and having means for the discharge of gas, a cooling-trap, and a valved connection between said trap and said separator, said connection and said trap forming a seal, substantially as described.

3. In a reclaiming apparatus for pulp-mills, the combination of a receiver, a drum, connections between said drum and receiver, a series of digesters, a series of separators, each connected to a digester and each of said separators having an independent valved connection with the receiving-drum, a cooling-trap for each separator, and independent connections between said traps and said separators, whereby one of the digesters may be disconnected without affecting the operation of the other, substantially as described.

1l. The combination with a digester and a receiver for the liquor and gas discharged therefrom during the cooking process, of connections between said digester and receiver whereby the liquor and gas vented from the di-Y gester are conveyed to the receiver and means for cooling said liquor and gas prior to the introduction thereof into the receiver, substantially as described.

5. In a reclaimer for pulp-mills, the combination of a digester, a separator connected therewith and having means for the discharge of gas, a cooling-trap, a Valved connectionbetween said trap and said separator, said connection and said trap forming a seal, a receiver and connections between the latter and the separator, substantially as described.

6. In a reclaimer for pulp-mills,the combination of a digester, a separator connected therewith and having means for the discharge of gas, a cooling-trap, a valved connection between said trap and said separator, said connection and said trap forming a seal, a receiver, connections between the latter and the separator, and means to cool the gas during its passage from the separator to the re` ceiver, substantially as described.

7; In a reclaiming apparatus `for pulp-mills a digester, a separator connected therewith,-`

a receiver connections between the latter and the separator to convey liquor and gas from* NELSON C. HOD GIiINS.

Witnesses:

J. W. GARNER, MAY G. GLADMOND.

IOO 

